摘要:

Hot off the Press Robert A. Hill' and Andrew R. Pitt2 'Department of Chemistry Glasgo w University Glasgow G 12 8QQ,UK. E-mail bobh@chem.gla.ac.uk Department of Pure and Applied Chemistry Strathclyde University Thomas Graham Building 295 Cathedral Street Glasgo w G 1 IXL UK. E-mail a.r.pitt@strath.ac.uk Reviewing the recent literature on natural products and bioorganic chemistry In NPR 'Hot off the Press' the authors aim to bridge the unavoidable gap between the compilation submission and publication of NPR's major articles by reviewing in a general way the literature of the preceeding few months and hence drawing attention to significant advances in the relevant fields. We have chosen to attempt to mirror the broad range of bioorganic chemistry now appearing in the review articles published in NPR covering subjects from areas as diverse as the identification of novel and interesting natural products new methods for analysis and significant new total syntheses to biotransformations important advances in molecular genetics and mechanistic enzymology.This will be inevitably our personal view of the articles of interest and importance from the recent literature and we apologize in advance to those who feel that we have missed some significant aspect. While we will not be able to enter into correspondence we would be grateful for any ideas comments or suggestions for this series of articles to which end we can be contacted on the following e-mail addresses a.r.pitt@strath.ac.uk bobh@chem.gla.ac.uk We hope that all that the readers of NPR will find something of interest in 'Hot off the Press '.The year 1995 will be remembered among other reasons for the notable total syntheses of some of the most complex natural products perhaps the most impressive of which is the brace of molecules completed by Nicolaou. Few people will have missed his total synthesis of Taxol@ (paclitaxel) (1) (an enlightening review of which by Nicolaou and Guy appears in Angew. Chem. Int. Ed. Engl. 1995 34 2079) to which he recently added the total synthesis of brevetoxinB (2) (J. Am. Chem. SOC. 1995 117 10227 10239 and 10252). His account of the synthesis of brevetoxin B revealingly tells not only of the final success but also of a few of the blind alleys encountered in the initial stages of the work.BzNH 0 OH 0 OBZ Synthesis also featured strongly at the 17th IUPAC Carbo- hydrate Conference abstracts of which appeared recently (Pure Appl. Chem. 1995 67 1609-1698). C.-H. Wong's Whistler Award lecture (p. 1609-1616) was particularly fascinating as he laid bare his strategies for the chemical and chemo-enzymatic synthesis of complex oligosaccharides. A number of the most senior figures in the bioorganic community presented papers at the 14th International Conference on Enzyme Mechanisms held in Arizona -this conference is reviewed by Kluger and Hamilton in Bioorg. Chem. 1995 23 263. Key speakers included Walsh Sessler Breslow and Verdine. Verdine has since put his outstanding work on the elucidation of the mechanism of base pair excision in DNA repair to good use in the rational design and synthesis of an inhibitor (3) of the enzyme involved (J.Am. Chem. Soc. 1995 117 10781). Weinreb has reported the synthesis of the unusual marine alkaloid papuamine (4) using a novel imino ene reaction to set up the required stereochemistry (J. Am Chem. Soc. 1995 117 10905). A discussion of recent publications on synthesis would not be complete without mentioning the complete issue of Chemical Reviews dedicated to the synthesis of biofunctional molecules (Chem. Rev. 1995 95(6) 1677-2260) the weight of the volume alone paying homage to the wealth of new work in the area. 0 DNA' (3) J J Since the discovery that TaxoP (1) has useful anticancer activity the search for new taxanes and new sources of Taxol has flourished.Well over 100 new taxanes and abeotaxanes have been isolated. The slow growth of Taxus species cannot keep pace with the demand for Taxol the bark and needles have been the traditional sources but recently Sun has found that the roots are a good additional source (J. Nat. Prod. 1995 ... 111 58 1153). Total syntheses cannot produce Taxol on an economic scale due to the complex nature of the structure so avenues have been explored using semisynthesis from other taxanes such as 10-deacetylbaccatin 111. Another possibility is to utilize genetic engineering to improve the biological production of Taxol. This requires a better understanding of the detailed biosynthetic pathways involved.To this end two of the key intermediates in Taxol biosynthesis taxa-4(20) 1 1 -diene and taxa-4,1l-diene have been synthesized (R. M. Williams and co-workers J. Org. Chem. 1995 60 7215) and we await the interesting developments in this field. (-)-Isolepidozene (5) has been identified in the liverwort Preissia quadrata and subsequently was also identified by GC-MS in several other liverworts (W. A. Konig et al. Phytochemistry 1995 40 605). The authors suggest that isolepidozene may have been misinterpreted as the diastereo- isomer (-)-bicyclogermacrene (6) during the analysis of the essential oils of liverworts by GC-MS. The NMR spectra of synthetic calonolide C (7) showed subtle differences to the natural product from Calophyllum inophyllum.The natural product has now been renamed pseudocalonolide C (8) and its structure revised on the basis of further analysis using long- range heteronuclear correlation experiments (HMBC) (M. R. Boyd et al. J. Nut. Prod. 1995 58 916). The annonaceous acetogenins are a class of potent bioactive compounds from various plant species in the Annonaceae. They typically contain one or several tetrahydrofuran rings. Now a new structural feature a hydroxytetrahydropyran ring has been found in mucocin (9) from Rollinia mucosa (J. L. McLaughlin et al. J. Am. Chem. SOC.,1995 117 10409). Irlbacholine (10) is an intriguing phosphate ester found in both Irlbachia alata and Anthocleista djalonensis (D. E. Brierer et al. J.Org. Chem. 1995 60 7022). Both plants have been used in traditional medicine and irlbacholine shows antifungal proper- ties. (9) 0 0 (10) Caledonin (1 1) from the tunicate Didemnum rodriguesi features a six-membered cycloguanidine moiety and a novel sulfur-containing p-amino acid (R. Riguera et al. Tetrahedron Lett. 1995 35,8853). Caledonin (11) shows strong binding to both Zn2+ and Cu' ions. Other new natural products with interesting structural features include longamide (12) from the marine sponge Agelas longissima with an unusual brominated NATURAL PRODUCT REPORTS. 1996 pyrrolopiperazine nucleus (E. Fattorusso et al. Tetrahedron Lett. 1995 35 7893) a rearranged steroid citreoanthrasteroid (13) from a hydrid strain of Penicillium citreoviride (S.Yamamura et al. Tetrahedron Lett. 1995 35 7481) and a secoamorphane (14) from the foliage of Cupressus macnabina that has a marked similarity to the secoamorphanes from Artemisia annua (L. G. Cool et al. Phytochemistry 1995 40 857). 0 H@?Br A new class of sesquiterpenoids the trifarienols such as trifarienol A (15) has been isolated from the liverwort Cheilolejeuna trifaria by Asakawa (Phytochemistry 1995 40 171). The trifarane skeleton may arise from an intermediate striatane sesquiterpenoid such as striatol A (16) that is found in the same liverwort. Emmotetene (17) from the gorgonium Briareum polyanthes has a previously unreported skeleton incorporating the first naturally occurring trans-bicyclo-[5.1.0]octane(J.H. Cardellina I1 et al. J. Org. Chem. 1995,60 6864). OH The cyclopropane theme continues with U-106305 (18) a cholesteryl ester transfer protein inhibitor from culture UC 11 136 (M. S. Kuo et al. J. Am. Chem. Soc. 1995,117 10629). The backbone has been shown to be polyketide derived while the cyclopropyl methylene carbons were derived from the methyl group of L-methionine. 13C NMR at 150.9 MHz has been used to follow the biosynthesis of methylursubin (19) from 4-methoxyphenol in vivo in cell suspensions of RauwolJia serpentina using natural abundance 13C (J. Stockigt et al. Phytochemistry 1995 40 801). The intermediacy of methyl- arbutin (20) was clearly demonstrated. NATURAL PRODUCT REPORTS 1996-HOT OFF THE PRESS IH Remarkable diastereo-and enantioselectivity has been demonstrated in the reduction of ethyl 2-methyl-3-oxobutanoate (21) by plant cell cultures of Marchantia polymorpha and Glycine max (K.Nakamura et al. Phyto- chemistry 1995 40 1419). The lipase from Pseudomonas cepacia has been used to resolve a range of alcohols (e.g. C. R. Johnson et al. J. Org. Chem. 1995 60 6675). The enantio- selectivity of this lipase has been extensively discussed by R. J. Kazlauskas (J. Org. Chem. 1995 60 6959). Cyclodextrin has been used to limit product inhibition of phenylalanine ammonia lyase. The cinnamate is selectively sequestered by the cyclo- dextrin increasing the efficiency of the reaction (C. J. Easton et al. J. Chenz. Soc. Perkin Trans. 1 1995 2525). ?H ),,C02Et 0 I 97% ee The debate on whether protein folding occurs on or off the ribosome continues with the demonstration of the folding of rhodanase with a 23 amino acid C-terminal extension into an active conformation while still bound to the ribosome (Kudlicki et al.Biochemistry 1995 34 14284) in the presence of all six V of the E. coli chaperonins. In the biosynthetic field after many years of debate the cloning of Al-tetrahydrocannabinolicacid synthase by Morimoto et al. has finally shed further light on the biosynthetic pathway to A’-tetrahydrocannabinolic acid (22) (J. Am. Chem. SOC.,1995 117 9766). The first hard mechanistic evidence is presented for a pathway involving a cannabigerolic acid (23) intermediate contrary to the generally accepted cannabidiolic acid route.I OH I C02H A’-tetrahydrocannabinolic & acidsynthase * C02H HO Cd11 Some work on the intriguing mechanism of 4-chlorobenzoyl- CoA dehalogenase has been reported (G. P. Crooks et al. J. Am. Chem. SOC.1995 117 10791). This postulates the formation of an arylknzyme intermediate as a consequence of nucleophilic attack by an active site carboxylate in an S,Ar mechanism. Mass spectrometry of biomolecules continues to be one of the main focuses of new techniques in the analysis of natural products. Attomole (10-l8mol) sensitivity of detection for peptides and phospholipids can be obtained using MALDI- FTICR (T. Solouki et al. Anal. Chem. 1995 67 4139) opening the way for the detection of very low concentrations of metabolites.The development of ‘in line’ processing of an injected sample in a microreactor (trypsin or carboxypeptidase digestion in this case) followed by separation of the reaction products by capillary electrophoresis and direct electrospray mass spectrometric analysis is progressing rapidly (L. Licklider et al. Anal. Chem. 67,4170) opening up new opportunities for the characterization of natural products. Mass spectrometry is not limited to size and sequence determination as demonstrated by Grieg et al. (J. Am. Chem. SOC.,1995,117,10765) who have used electrospray mass spectrometry to measure the dis- sociation constant of the macromolecular complex between an oligonucleotide and serum albumen.

ISSN:0265-0568    

DOI:10.1039/NP996130iiia

出版商:RSC    

年代:1996

数据来源: RSC